Nowadays the use of laundry washing machines, both “simple” laundry washing machines (i.e. laundry washing machines which can only wash and rinse laundry) and laundry washing-drying machines (i.e. laundry washing machines which can also dry laundry), is widespread.
In the present description the term “laundry washing machine” will refer to both simple laundry washing machines and laundry washing-drying machines.
Laundry washing machines generally comprise an external casing provided with a washing tub which contains a rotatable perforated drum where the laundry is placed.
A loading/unloading door ensures access to the drum.
Laundry washing machines typically comprise a water inlet circuit and a products supply unit for the introduction of water and washing/rinsing products (i.e. detergent, softener, etc.) into the tub.
Known laundry washing machines are also provided with water draining devices that may operate both during the initial phases of the washing cycle and at the end of the same to drain the dirty water.
According to the known technique, a complete washing cycle typically includes different phases during which the laundry to be washed is subjected to adequate treatments.
A washing cycle usually comprises a laundry wetting phase with addition of a washing detergent and a main washing phase during which the drum is rotated and the water contained therein is heated to a predetermined temperature based on the washing program selected by the user. During the main washing phase the drum is rotated, so as to apply also a mechanical cleaning action on the laundry. At the end of the main washing phase the drum is typically rotated at high rotational speed, in such a way that dirty washing liquid (i.e. water mixed with detergent) is extracted from the laundry, and this dirty washing liquid is drained by the water draining devices.
A successive step of the cycle typically comprises a rinsing phase which usually comprises one or more rinsing cycles. In the rinsing cycle, clean rinse water is first added to the laundry, so as to be absorbed by the laundry and remove from the latter detergent and/or dirty particles not previously removed by washing liquid, and then the drum is rotated to extract water and dirty particles/detergent from the laundry: the dirty water extracted is drained from the tub to the outside by the water draining devices.
After the rinsing phase, a final spinning phase allows the extraction of the residual water contained in the wet laundry.
The water extracted during the spinning phase is drained towards the outside by means of the water draining devices (during or after the spinning phase).
A laundry washing machine performing a washing cycle is disclosed in document EP1967634A2.
Such laundry washing machine comprises a tub having a cylindrical structure for containing washing water and a rotary drum rotatably installed in the tub.
The machine further comprises a heater for heating washing water. The heater is installed in the lower portion of the tub. The machine comprises a washing device for spraying washing water to the heater to wash the heater.
The washing device substantially comprises a recirculating circuit provided with a recirculating pump which withdraws liquid from the bottom of the tub and sprays said liquid to the heater through a spray nozzle. The sprayed liquid washes the heater by removing substances stuck to the heater.
The spray nozzle is installed below the heater so that the washing liquid is vertically sprayed against the heater from below.
However, the laundry washing machines of the known art pose some drawbacks. A drawback posed by the laundry washing machines of the known art is that the washing products, or the rinsing products (e.g. laundry softener), which are introduced into the washing tub during the washing cycle, move towards the bottom part of the tub, due to their high density and, therefore, tend to accumulate on the bottom of the tub.
Accumulation of these products does not ensure a complete and/or a fast dissolution of the products themselves in the water. It is well known that a fast and/or complete dissolution has a positive impact on the washing performance. Due to such undesired accumulation of products, therefore, the machine of known type does not have a high efficiency.
Furthermore, washing performance may be different for each washing cycle depending on the percentage of product which accumulates on the bottom of the tub and hence does not completely dissolve.
Therefore, the washing performance may vary from time to time and cannot be properly controlled.
Another drawback deriving from accumulation of washing/rinsing products in the bottom of the tub is that the sedimentation of such products may favour the proliferation of bacteria, which may then worsen the hygienic conditions and may cause bad smells.